Zinc (Zn) and iron (Fe) are essential for cognition. Red meat is the best common source of Zn and Fe deficiencies. Avoidance of red meat and recurrent bleeding increases the risk of Zn and Fe deficiencies. Some premenopausal women consume little if any red meat. Thus they are at risk of impaired cognition. The project measures the effects of repletion of Zn and/or Fe nutriture on neuropsychological function of premonopausal women through a double blind stratified randomized controlled treatment with crossover design. Deficient subjects are identified by food frequency history and serum ferreting concentration. Zn deficiently is confirmed by measurement of plasma Zn and hair Zn. Sixty deficient and 20 normal subjects are studied. Other potentially deficient micronutrients are repleted before the experiment begins. Twenty deficient and the 20 normal control subjects are repleted with other micronutrients (M) for 16 weeks, with a pseudo-cross over after 8 weeks. Then treatments they are switched (crossover) and treatment is continued for 8 weeks. Neuropsychological function is measured before treatment (baseline) and after 8 and 16 weeks of treatment. Individual and combined effects of Zn and Fe, and unique effects related to the order of treatments are determined. Other outcomes include: (a)Improved inductively couple plasma-mass spectroscopy ICP-MS methods for measurement of Zn tracers and assessment of Zn status by zinc kinetics. (b) Demonstration of relationships between body zinc pools and lean body mass. (c) Demonstration of relationships between indices of Zn status and other indices of metabolism that might be related to Zn status such as plasma pyridoxal-5 phosphate, folate, cyanocobalmine, hydroxproline and free amino acids.